Light beam projecting range finder



M. SCHWARTZ ET AL LIGHT BEAM PROJECTING RANGE FINDER May 11, 1954 2Sheets-Sheet 1 Filed Jan. 14, 1955 j WH HM 7 n y w. 1 9 W 0 j z 4 M.SCHWARTZ ET AL LIGHT BEAM PROJECTING RANGE FINDER Filed Jan. 14, 1953 2Sheets-Sheet 2 Patented May 11, 1954 LIGHT BEAM PROJECTING RANGE FINDERMorris Schwartz and William Castedello, Plainville, Conn, assignors toThe Kalart Company Inc., Plainville, Conn.

Application January 14, 1953, Serial No. 331,192

13 Claims.

This invention relates to a light beam projecting photographic rangefinder, particularly to a range finder of this type which is attachableas an accessory to the casing of a camera.

There are already known several designs of a light beam projecting rangefinder attachable to a camera with a drop bed and a bellows between theobjective carrier and the camera casing. However, there is not as yetavailable a light beam projecting range finder that is suitable forcameras of the type in which the objective carrier forms the front wallof the camera casing and is movable relative thereto by means of afocusing knob, in particular for reflex cameras.

One of the principal objects of the present invention is to provide alight beam projecting photographic range finder which can beconveniently attached to a casing of the camera of the general type,above referred to, particularly to a reflex camera, for instance, of thetwin-lens reflex type such as the Rolleifiex.

According to the invention, a light beam projecting range findersuitable for cameras in which the objective carrier forms the front wallof the camera casing and is movable relative thereto by means of afocusing knob is attained by disposing the source of current for therange finder within a casing which is provided with holding means fordetachably securing the finder casing of the bottom of the camera casingin a predetermined position relative thereto; by disposing the opticalsystem of the range finder and the moving mechanism for adjusting theoptical system in accordance with the range to be determined within asecond casing fixedly mounted on the first mentioned casing in aposition providing for an unimpeded focusing movement of the objectivecarrier, and by providing an actuating member forming part of the movingmechanism and extending into the path of the objective carrier movementfor actuation by the said movement, thereby adjusting the range finderin conformity with the focusing of the camera.

According to a further improvement of the invention, the outline of thecasing housing the source of current matches substantially the outlineof the bottom of the camera casing, and the second casing housing theoptical system and the moving mechanism is disposed in a position inwhich the center axis between the beam projecting windows of the rangefinder is parallel to the bottom of the camera casing.

A switch for closing a circuit for the light bulb of the range finder ispreferably mounted in one of the side walls of the casing housing thesource of current.

The entire range finder is preferably attachable to the camera casing bymeans of a screw fitting the tripod hole of the camera casing, and aflash bulb holder can be attached to the range finder by means of abracket fastened to the casing of the range finder housing the source ofcurrent.

For the purpose of attaching the range finder to the camera casing inthe proper position for adjusting the optical system of the finder inaccordance with the focusing position of the objective carrier, guideposts protrude from the top wall of the casing housing the source ofcurrent which posts are engageable with legs extending from the bottomof the camera casing. At least one of the guide posts and the legs inengagement with each other are complementarily shaped so as to extendone into the other thereby fixing the position of the range finderrelative to the camera casing.

The moving mechanism of the range finder includes a pin-like memberengageable with the objective carrier and supported on a pivotal lever.This lever is coupled with the pivotal reflector of the range finder sothat a displacement of the objective carrier causing a pivotal movementof said lever by means of the pin will effeet a corresponding angularadjustment of the pivotal reflector.

In the accompanying drawing a now preferred embodiment of the inventionis shown by way of illustration and not by way of limitation.

In the drawing:

Fig. 1 is a perspective view of a light beam projecting range finderassembly according to the invention attached to a reflex camera, thecamera being shown in phantom.

Fig. 2 is a side view of the range finder assembly attached to thecamera casing.

Fig. 3 is a plan view of the range finder assembly.

Fig. 4 is a fragmentary plan view of the range finder assembly, partlyin section.

Fig. 5 is a section taken on line 5-5 of Fig. 4.

Fig. 6 is a section taken on line 6-6 of Fig. 5 and Fig. 7 is alongitudinal sectional view of the optical system and the movingmechanism of the range finder.

As is well known to persons skilled in the art, light beam projectingrange finders of the type, herein referred to, comprise a stationaryreflector, such as a mirror, and a pivotal reflector, such as a mirror,which are disposed one with the other and with a source of light, such.as an incandescent light bulb, in an optical relationship so that twolight beams are projected by the two reflectors. The beam emanating fromthe stationary reflector has a fixed angular position, whereas theangular position of the beam emanating from the pivotal reflector iscontrolled by the position of this latter reflector. The beams producetwo light spots on the object, the range of which is to be determined.The pivotal reflector is coupled by a moving mechanism with theobjective carrier of the camera so that the angular position of thepivotal reflector is controlled by the focusing position of the saidcarrier. It will now be apparent that an adjustment of the objectivecarrier will vary the relativ position of the lig t spots. The ratio oftransmission of the moving mechanism is so arranged that the camera iscorrectly focused when the two light spots are in a predeterminedrelative position, for instance in a superimposed position.

Referring now to the figures in detail, the range finder assemblysubstantially rectangular large is and a smaller casing ll secured tocasing ill. Casing ill houses one or more batteries iii as source ofcurrent for the light bulb of the range finder. The batteries areconnected in series by suitable spring contacts 53, as can best be seenon Fig. 3. The optical system of the range finder is disposed withincasing l l which also houses or supports the moving mechanism of therange finder. As was previ ously explained and can best be seen on Fig.7, the optical system of the range finder comprises a stationary mirrori i, pivotal mirror It and lenses 35, fitted in windows 36. Mirror I issecured, for instance by cementing, to a bracket is one end of which isscrewed to a wall of housing it by means of screw ii. The free end ofthe bracket is engaged by a set screw [8 for the purpose of adjustingthe position of mirror it within certain narrow limits. Mirror i iscemented to a mounting il pivctally supported by a pin 2b. An ill frommounting is and engaged at its free end by a short, preferably curvedlever secured to a pivot 23. As can best be seen on 5, this pivot ispivotally extended through casing ii and supports at its end rotrudingfrom the top wall of easing H a lever This lever has on its free end apin the function of which will be more fully explained hereinafter. Itsuilices to at the present time that a piovtal movement of lever 24 willcause a corresponding pivotal movement of mirror i Springs 2% and illserve to hold the hereinbefore described movement transmitting con entsin engagement.

The sou ce of light of the rang finder is shown small bulb filament illof which is in the form of disposed in axial alignment with the opticalcenter axis between mirrors M and i5. Bulb and mirrors it and I5 causethe projection of two light beams through lenses and 35?. Light beam 8is stationary and the light lvi movable relative to the S. reason of thecoil shape of filament 3!, the light spots produced by the two beamstake the form of small which has the advantage that the two light spotscan be conveniently placed in an accurate super-imposed position. Thetwo light beams are projected from casing ll through the lenses in thewindows 35 and 36 which are of conventional design.

Bulb 3b is mounted by means of a substantially rectangular insulationblock secured to casing l i by screws ll. Block ii! is provided with abore 42 in which is fitted a metal sleeve 43 receiving a socket M forthe base of bulb 30. The

lower face of sleeve 43 is provided with a groove engaged by pinsextending from socket 44 for the purpose of fixing the bulb in aposition in which its coil filament is aligned with the optical axisbetween the two mirrors. The bulb is held in sleeve 43 by means of aspringy metal plate 4% secured to insulation block All! by means of ascrew ll. Plate 45 engages the bottom terminal of bulb 30 as can best beseen on Figs. 5 and 6.

For the purpose of connecting the bottom terminal of the bulb to thebatteries, a contact plug 58 is fitted in insulation block it. Plug isin electric contact with screw 41 and engages with its end extendinginto casing it through an opening 5! in the front wall oi this casing acontact spring 52 abutting against one of the terminals of the batteryl2 shown on the right side of Fig. 4. Socket M is engaged by a screw 53which supports a flexible contact strip ti l. The screw forms onecontact element of a switch, th other contact element of the switchbeing formed by a contact strip the shape of which can best be seen onFig. l. Contact strip 55 is in electric contact with a contact plugfitted in a bore of insulation block ii) by means of a screw 51. Plug 56engages a contact spring 53 which in turn abuts against a terminal ofthe battery i2 shown on the left side of Fig. l. Contact elements 54 andare biased into a disengaged position (as shown on Fig. 6). A. switchbutton 59 secured to contact lement 5% serves to establish connectionbetween contact elements and 55 by pressing button 58 toward casing it.The switch preferably mounted in the front side wall of easing iii. Aswill now be apparent, actuation of button 5:! will close a circuit forbulb 3B.

e op side of casing is closed by a cover plate which may be secured tothe casing by means of screws 66. The front edge of plate 6'5 is bentupwardly to form a bracket to to which cas n ll secured by means of srews all.

An insu casing to culate the batteries from the casing and the cover andis secured to the cover by screws ill.

The outline of easing it corresponds preferably approximately to thebottom of the casing of a camera ill in conjunction with which it isintended to use the range finder. The camera is shown as reflex camera,the objective carrier ll of which forms the front wall of the camera Asis conventional with cameras of this type, operation 01' the focusingknob of the camera moves the objective carrier back and forth relativeto the casing proper. As can best be seen on l s. 1 and 2, casing i I isso arranged that it is in front of the camera casing but does not imnodethe focusing movements of the objective carrier. The longitudinal axisof easing H is parallel to the plane of the bottom of the camera casing,and the two beam windows of the finder are equidistant irol the, centerof camera objective to facilitate aiming of the camera.

The aforementioned pin 25 engages the objective carrier ll. As a result,the pivotal position of lever 24% and, hence, of mirror 15 will becontrolled by the focusing position of the objective carrier 5 i. Aheaded screw .7 5 serves to limit the follower movement of lever 24 whenobjective carrier l! is in a retracted position.

The entire range finder assembly is detachably secured to the bottom or"the camera casing by any suitable means such as a screw 56 which isextended through holes ll in casing Ill and threaded into the tripodhole l8 of the camera.

7. lion lining 9b is provided within the As will be apparent from theprevious description, it is essential that the range finder assembly isalways secured. to the camera casing in a definite position since avariation of this position would upset the range adjustment of thefinder. For the purpose of facilitating mounting of the range finder inthe said definite position, two pairs of legs or guide posts at and s:extend from cover 85 of casing ill. These legs engage correspondingpairs of legs 82 and 33 extending from the bottom of the camera casing.As can best be seen on Fig. 2, legs 8! and 83 have fiat engaging faceswhile legs as and 82 are recessed and tapered respectively so that thelegs 8%} and 82 engage each other thereby fixing the range finder in itsposition relative to the camera casing. Instead of providing engagingfront legs it is, of course, also possible to provide engaging rearlegs. Furthermore, all four pairs of legs may engage each other ordiagonal pairs of legs may be in engagement.

One of the screws 56 can also be used to support a bracket $5 for aflash bulb holder of conventional design which may be slipped upon ashoe 3B of the bracket. Screw it is preferably provided with a threadedbore 92 to receive the tripod screw.

What is claimed. to be new, is:

1. A light beam projecting photographic range finder attachable to aphotographic camera having a casing the front wall of which forms theobjective carrier of the camera and is movable by means of the focusingknob of the camera, the said range finder comprising a first closedcasing for a source of current for the range finder, fastening means onthe casing for detachably securing the same to the bottom of a cameracasing in a predetermined position relative thereto, a second closedcasing fixedly mounted on the first casing in a position providing foran unimpeded movement of the objective carrier, an optical system forprojecting two light beams angularly movable relative to each other, anda moving mechanism for adjusting the relative angular position of thetwo beams disposed within said second casing, the said moving mechanismincluding an actuating means protruding from said second easing into thepath of the objective carrier movement and engageable with saidobjective carrier for transmitting the focusing movement of theobjective carrier to said moving mechanism thereby adjusting the latterin conformity with said focusing movement.

2. A range finder according to claim 1, wherein the peripheral outlineof said first casing is substantially rectangular and matchessubstantially the peripheral outline of the bottom portion of a cameracasing to which it is attachable, and wherein the said optical systemcomprises two lens means mounted in a wall member of the second casingspaced apart in a position in which the center axis between the two lensmeans is situated parallel to the plane of the bottom of a camera casingto which the range finder is attached.

3. A range finder according to claim 2, wherein the said second casinghas a substantially rectangular eripheral outline, and wherein the saidtwo lens means are positioned equidistant from the optical center axisof the camera objective.

i. A range finder according to claim 1, wherein the second casing issecured to one of the side edges of the top wall of said first casingparallel to said edge.

5. A range finder according to claim 4, wherein the said top wall isformed with a flange protruding therefrom, the said flange constitutinga support for said second casing.

6. A range finder according to claim. 1, wherein the said optical systemincludes a light bulb connectable in circuit with a source of currentdisposed in said first casing, and wherein a switch means is included insaid circuit for illuminatins said light bulb by closing of the switchmeans.

'7. A range finder according to claim 5, wherein the said switch meansis mounted adjacent to one of the walls of said first casing.

8. A finder according to claim 1, in combination with a bracket for aflash bulb holder attachable to said first casing.

9. A range finder according to claim 1, where in the said first casinghas a transverse hole therethrough, and wherein a screw is fittedthrough said hole retained therein, the said screw being adapted to bethreaded into the tripod hole of a camera casing.

10. A range finder according to claim l, wherein the said fasteningmeans comprise guide posts upwardly protruding from the top wall of thefirst casing, the said guide posts being engageable with legs extendingfrom the bottom of the camera casing, at least two guide posts and twolegs in engagement with each other being complementarily shaped so as toextend one into the other thereby fixing the position of the rangefinder relative to the camera.

11. A range finder according to claim 1, wherein the said optical systemincludes a stationary light deviating means, a pivotal light deviatingmeans and a light bulb disposed in the optical center axis between saidtwo light deviating means for causing the same to project the said twolight beams, a lever pivotally mounted on the outside of said secondcasing and operatively connected with said pivotal light deviating meansfor pivotal movement in unison therewith, and a pin extending from saidpivotal lever and engageable with said objective carrier for'moving thepivotal light deviating means into an angular position corresponding tothe focusing position of the objective carrier.

12. A range finder according to claim 11, wherein the said connectionbetween the pivotal light deviating means and the pivotal levercomprises an arm extending from said pivotal light deviating means anddisposed within the second casing, a pivot rotatably extending throughthe top wall of said second casing, the end of said pivot within thesecond casing engaging said arm and the end of the said pivot outsidethe casing being secured to said pivotal lever, and loaded spring meansbiasing said arm and said lever into a movement transmitting engagement.

13. A range finder according to claim 11, wherein an insulation blockincluding a here is secured to a Wall of said second casing on theoutside thereof, the said light bulb being fitted in said bore so as toextend into the interior of said second casing and in the axis betweenthe two light deviating means, and wherein a metal plate releasablyattached to said insulation block retains said bulb in said bore, thesaid metal plate engaging one of the terminals of the bulb andconnecting the said terminal with a source of current in said firstcasing, the other terminal of the bulb being connectable to the sourceof current.

No references cited.

